Value quantities

China also produces a small quantity. Values are estimated. 

Table 3 Hsts only those carboxyHc acid esters whose 1990 U.S. production, sales quantity, value, and raw materials have been pubHshed (95). They are grouped on the basis of their principal use. For a complete Hst of the organic esters produced and sold in the United States and their manufacturers, the original pubHcation should be consulted. Uses of some specific esters are also given in Table 4.

Table 2.2 Physical properties of the Milky Way Quantity Value...

The Joule-Thomson coefficient p.jx, is positive when a cooling of the gas (a temperature drop) is observed because dP is always negative, p.j x, will be positive when dT is negative. Conversely, p.j x, is a negative quantity when the gas warms on expansion because dT then is a positive quantity. Values of the Joule-Thomson coefficient for argon and nitrogen at several pressures and temperatures are listed in Table 5.5. 

Accuracy is the closeness of a result to a true value. This again is the combination of tmeness and precision and defines measurement uncertainty. (See also chapter 12). Accuracy is greater when the quantity value is closer to the tme value... 

Closeness of agreement between a measured quantity value and a true quantity value of a measurand [vim]... 

Tha concept measurement accuracy is not a quantity and is not given a numerical quantity value [VIM]. 

Closeness of agreement between indications or measured quantity values... 

Closeness of agreement between the average of an infinite number of replicate measured quantity values and a reference quantity value [VM]... 

Quantity value consistent with the definition of a quantity [VIM]... 

Measurement is the process of experimentally obtaining one or more quantity values that can reasonably be attributed to a quantity Measurement procedure is the detailed description of a measurement. An operator should be able to measure a measmand following the description. 

Realization of the definition of a given quantity, with stated quantity value and associated measurement uncertainty, used as a reference [VIM]... 

Error (of measurement) is the sum of random and systematic errors of one measurement. Since a true value cannot be determined, in practice a reference quantity value is used. Each individual result of a measurement will have its own associated error. 

But what is a measurement Measurement is obtaining a measurement result - a quantity value and an uncertainty. 

Precision is the closeness of agreement between indications or measured quantity values obtained by replicate measurements on the same or similar objects under specified conditions. 

Trueness The closeness of agreement between the average of a infinite nimber of replicate measure quantity values and a reference quantity value [VIM] Precision closeness of agreement between indications ormeasLFed quantity values obtained by replicate measurements on the same or similar objects under specified conditions [VIM]... 

Non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used"... 

The term factor is a catch-all for the concept of an identifiable property of a system whose quantity value might have some effect on the response. Factor tends to be used synonymously with the terms variable and parameter, although each of these terms has a special meaning in some branches of science. In factor analysis, a multivariate method that decomposes a data matrix to identify independent variables that can reconstitute the observed data, the term latent variable or latent factor is used to identify factors of the model that are composites of input variables. A latent factor may not exist outside the mathematical model, and it might not therefore influence... 

Samples distributed for analysis should have known quantity values with estimated measurement uncertainties, although, of course, these are not released to the participants until after the tests. The value of the measurand ( assigned) can be assigned by... 

A formulation using materials of known composition and certified quantity values. 

Because a consensus value does not guarantee a correct result, the use of interlaboratory studies to establish the quantity value of a would-be reference material must be undertaken with great care. A traceable quantity value per se is not established by the consensus of a number of laboratories, but if each of those laboratories can demonstrate that they have reported a traceable... 

The organizer of an interlaboratory study to assign a quantity value to a reference material is usually a national or international certifying authority, such as the International Atomic Energy Agency (United Nations), the Community Bureau of Reference (European Union), or a national measurement institute. 

The results of IMEP-1 clearly pointed to the problem of lack of equivalence of measurement results and demonstrated that studies needed to use independently established quantity values. IMEP operated from the beginning under the auspices and with the support of the International Union of Pure and Applied Chemistry, EURACHEM, the Association of European Metrology Institutes, and Cooperation in International Traceability in Analytical Chemistry. 

If there is any doubt about whether 100% of the analyte is presented to the measuring system or that the response of the calibrated system leads to no bias, then the assumptions must be tested during method validation and appropriate actions taken. If a series of measurements of a CRM (not used for calibration) leads to the conclusion that there is significant bias in the observed measurement result, the result should be corrected, and the measurement uncertainty should include the uncertainty of the measurement of the bias. If the bias is considered insignificant, no correction need be made, but measuring the bias and concluding that it is zero adds uncertainty (perhaps the bias was not really zero but is less than the uncertainty of its measurement). One approach to measurement uncertainty is therefore to include CRMs in the batch to be used to correct for bias, and then the uncertainty of estimation of bias, which includes the uncertainty of the quantity value of the CRM, is combined with the within-laboratory reproducibility. In some fields of analysis it is held that routine measurement and correction for bias... 

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